"A unique magic seal that can be placed on any other Item. When placed, the affected Item's effect becomes refined, causing it to become stronger via simplification and reformation. The seal then disappears, leaving behind the altered item. The Refinement Seal cannot fail." -Item Encyclopedia
The Refinement Seal is one of three known alchemistic seals in Attack on Lololo 4, used to refine an item's effects. It is most commonly used on weapons.
The Refinement Seal employs the use of Alchemy to refine items, removing rust and reducing the item's negative properties. The Refinement Alchemy skill emulates the effect of this item, without the guaranteed chance of success.
Seals so far are not considered rare, but appear in limited numbers after a Wave ends. It is unknown what would happen if a Refinement Seal was applied to another seal, of the same type or different.